1000 electrical maintenance question and answers pdf

 What is armature reaction?
Armature reaction is the effect of armature flux on the main field flux.
The effects of armature reaction are follows.
a. Armature reaction destroys (cross magnetizes) and weakens the main field flux
produced by the main pole.
b. It causes to reduce the induced emf in the armature.
c. It causes to reduce the efficiency of machine.
d. It causes to produce sparking at the brushes due to the shifting of M.N.A
(magnetic neutral axis).
e. At short-circuited loads or at very heavy loads, in case of self-excited generators
de-magnetising of pole cores (wiping of residual magnetism) may takes place.

 What is the cooling water used in moderator heat exchanger during normal
operation? And during class IV failure?
During normal operation process LP water is used in moderator heat exchangers,
which transfers heat to seawater. During class IV failure firewater is used for the
moderator heat exchanger.

 During loca how the cooling of fuel bundle is achieved?
During loca there is provision for taking D2O from the moderator system, which is
connected to PHT system for fuel cooling and there is one more option for the
cooling of the fuel from the fire water system.

 What is transformer?
Transformer is a static device by which AC power at one voltage in one circuit will
be transformed into AC power of same frequency at another (decreased or
increased voltage) or same voltage to an another circuit, which is in mutual
inductive influence with the previous circuit and it is based on mutual electro
magnetic induction.